A very minor suggested correction to your first sentence.  Hope that it helps!

You wrote:

"I'm very interested in learning English and I can help you with russian language."

Either of the following would be correct options:

"I'm very interested in learning English and I can help you with the Russian language." 

-or-

"I'm very interested in learning English and I can help you with Russian."

(If you add the definite article, you need to have the word 'language'.  If you don't use the definite article, then you can just use the word 'Russian'.)

I'm very interested in learning English and I can help you with russian language

Hello! I'm very interested in learning English and I can help you with russian language. So I would be happy if we could do a language and culture exchange! =)